1. Field of the Invention
The present invention relates to systems for transferring a work piece from a loading location to a processing location. More particularly, but not necessarily exclusively, the present invention relates to welding systems in automobile assembly lines. For example, the invention may be applied to a parts loading jig which is transferred between a welding station and a loading station.
2. Description of the Related Art
The auto industry has, in recent years, seen significant improvements in work place efficiencies. Robots are able to perform certain repetitive tasks with improved repeatability and accuracy.
It is common, for example, to have robots weld the vehicle sub-assembly components on a jig which holds the component parts of the sub-assembly in position at a welding station. Conventionally, the jig is transferred to a loading station which is a safe distance from the welding station to prevent injury. The jig is then xe2x80x98tiltedxe2x80x99 to an angle making it more readily accessible to the assembly associate to load the jig.
Two drive units are normally used to perform these functions; one to transfer the jig between the welding and loading stations, and the other to xe2x80x98tiltxe2x80x99 the jig once it arrives at the loading station. The two drive units are independent, which means they have to be programmed and maintained separately, adding expense to the assembly process.
It is therefore an object of the present invention to provide a more efficient and cost effective transfer system.
It is another object of one embodiment of the present invention, to provide a transfer system for use in a welding installation wherein the transfer and tilt functions can are carried out by a single drive unit.
In one of its aspects, the present invention provides an apparatus for transferring and tilting a work piece, said apparatus comprising:
a transport carriage assembly for motion along a guide track having a limit position; the transport carriage assembly further comprising:
a first carriage member, said first carriage member being pivotally connected to a first linkage arm at a first pivot point, and
a second carriage member pivotally connected to a second linkage arm at a second pivot point, said first and second linkage arms being pivotally connected to one another at a third pivot point; and,
a work piece support coupled with the second carriage member wherein, under a drive force, the transport carriage assembly travels along the guide track, until the second carriage member reaches the limit position, whereupon the first carriage member continues to move, decreasing its relative distance from the second carriage member and simultaneously causing the first linkage arm and the second linkage arm to pivot about the third pivot point, thereby causing the work piece support to tilt.
In one embodiment, the apparatus has a drive unit for driving the carriage assembly along the guide track. The drive unit has a drive motor and a transmission portion arranged to displace the first carriage member, and consequently the second carriage member, relative to the guide track. Desirably, the drive motor is a servo motor.
In another aspect of the present invention, there is provided a transfer device comprising an undercarriage with two or more carriage portions which are movable along a travel path between a first location and a second location, the carriage portions carrying at least one work piece support, a linkage extending between the carriage portions and which is operable to change the position of the work piece support when one carriage portion moves relative to another along the travel path. In one embodiment, the carriage portions are confined to a linear travel path and one of them is stationary during the period of relative moment between the carriage portions. The work piece support is movable between a work piece transfer position and a work piece loading position. The linkage has two pairs of arms which are pivoted together at a common pivot location and to a corresponding carriage portion at each end. The work piece support, which is fixedly attached to one of the pairs of arms near said common pivot location, is in a generally horizontal orientation at one of said locations and is inclined at the other of said locations.
Preferably, a limit station is provided on the travel path to limit movement of one of said carriage portions along the travel path. A releasable anchor portion is also provided for removably anchoring one of said carriage portions as the other carriage portion travels along the travel path.
In still another of its aspects, the present invention provides a transfer device for transferring a work piece from a loading station to a welding station, comprising an undercarriage with at least two carriage portions, which are movable along a travel path between the loading station and the welding station, the pair of carriage portions carrying at least one work piece support, a drive unit for driving the carriage portions along the travel path and a linkage joining the carriage portions. The linkage is operable to change the orientation of the work piece when one carriage portion moves relative to the other carriage portion along the travel path.
In yet another of its aspects, the present invention provides a welding installation comprising a welding station, a loading station and a transfer device for transferring a work piece between the stations. The transfer device has a work piece support and an undercarriage with two or more carriage portions. The carriage portions are movable by a drive unit along a travel path between the loading station and the welding station. The carriage portions are interconnected by a linkage which is operable to change the orientation of the work piece support when the position of one carriage portion changes relative to the other along the travel path.
In yet another aspect of the present invention, there is provided a method of transferring work pieces between a loading station and a welding station, comprising:
a. providing a work piece support;
b. supporting the work piece support on a carriage; equipping the carriage with a pair of carriage portions which are movable along a travel path; and
c. providing a linkage between the work piece support and the carriage portions which is capable of changing the orientation of the work piece support when one carriage portion travels relative to the other carriage portion along the travel path.
In still another aspect of the present invention, there is provided a transfer device for transferring a work piece between a loading station and a welding station, comprising:
a. undercarriage means with at least two of carriage means, the carriage means movable independently of one another along a travel path between the loading station and the welding station;
b. work piece support means supported by the undercarriage means;
c. drive means to transfer said carriage means between the loading and welding stations; and
d. linkage means joining the carriage means for orienting the work piece support means between a transfer portion and a loading position; wherein the linkage is actuated when one carriage means moves relative to the other carriage means along the travel path.
In still another of its aspects, there is provided a method of transferring work pieces between a loading station and a work piece processing station, comprising:
a. a step for providing a work piece support;
b. a step for supporting the work piece support on a carriage;
c. a step for equipping the carriage with two or more carriage portions which are movable along a travel path; and
d. a step for providing a linkage between the work piece support and the carriage portions which is capable of changing the orientation of the work piece support when one carriage portion travels relative to the other carriage portion along the travel path.